In one known type of metal vapour laser, solid metal is distributed along the length of a laser tube. The metal vapour used in the lasing process is produced by heating the solid metal, the vapour then being excited to obtain a population inversion and laser action. The operating temperatures of such lasers having copper vapour as the amplifying medium are typically around 1500.degree. C. Considerable thermal insulation is required around the laser tube to maintain these conditions.
In another known type of metal vapour laser, the metal vapour which is used as the laser amplifying medium is derived from a metal halide compound. For example, copper vapour may be derived from copper bromide which is introduced into a laser tube and subsequently heated to cause it to vaporise and dissociate. The temperatures required for efficient operation of a metal halide laser are lower than those for metal vapour lasers in which the vapour is derived from solid metal charges, for example a laser employing copper bromide need be heated to only around 600.degree. C. The amount of thermal insulation required is thus reduced and fast start up times may be achieved.
The present invention seeks to provide an improved metal vapour laser apparatus.